Hand-Held NIR Spectrometry. Part II: An Economical No-Moving Parts Spectrometer for Measuring Chlorophyll and Moisture

2002 ◽  
Vol 56 (6) ◽  
pp. 720-724 ◽  
Author(s):  
W. F. McClure ◽  
David Moody ◽  
D. L. Stanfield ◽  
Osamu Kinoshita
Keyword(s):  
Low Cost ◽  
Frequency Converter ◽  
Silicon Detector ◽  
Developed Countries ◽  
Analog To Digital ◽  
Light Emitting ◽  
Digital Hardware ◽  
And Performance ◽  
Frequency Detector ◽  
Moving Parts

The design and performance of a low-cost no-moving-parts handheld NIR spectrometer are discussed. Dubbed the TWmeter, this device was conceived for use by researchers and others in developing countries unable to afford more costly technology found in developed countries. Two design features contribute to the novelty of this spectrometer: (1) three unfiltered light emitting diodes (LEDs) with peak emissions at 700, 880, and 940 nm for measuring chlorophyll in plant tissue and moisture in paper, and (2) a silicon intensity-to-frequency detector (a silicon detector with an integral voltage-to-frequency converter). The latter feature allows an ordinary microcomputer to obtain intensity measurements by counting for a fixed length of time, thus avoiding the need for higher-priced analog-to-digital hardware. Performance tests, using multiple linear regression for calibration, demonstrate that chlorophyll and moisture can be determined with a root mean squared standard error of prediction of 0.99 mg/cm2 of leaf surface for a range of 1–8 mg/cm2 and 1.04% (wet basis) for a range of 30–65% moisture, respectively. Development of the TWmeter (costing less than $300 US), demonstrates that spectrometry need not be costly.

scholarly journals What does the Shinyei PPD42NS Low-Cost Dust Sensor Really Measure?

2021 ◽  
Vol 12 (1) ◽  
pp. 1-9
Author(s):  
Michaël Canu ◽  
◽  
Boris Gálvis ◽  
Malika Madelin
Keyword(s):  
Particulate Matter ◽  
Low Cost ◽  
Developed Countries ◽  
The World ◽  
Detection Stage ◽  
Sensor Signals ◽  
Precision And Accuracy ◽  
And Performance ◽  
Accuracy And Repeatability ◽  
Particulate Matter Pollution

Deteriorating air quality is of great concern around the world. Recently, citizen scientists, researchers, and many others have used low-cost devices such as the Shinyei PPD42NS dust sensor to measure particulate matter pollution in both developed and under-developed countries. However, few articles exist specifically on the features and performance of these sensors. Some have shown mixed results in terms of precision, accuracy, and repeatability, especially for portable applications. Frequently, users assemble the electronics and the sensors applying simple guidelines, using electric schematics, and coding extraneous algorithms to get questionable data. There is a need to better understand how it works exactly, its limitations and the effect of the program used to interpret the outputs of this sensor. This article provides a short electronic analysis of the Shinyei PPD42NS dust sensor and shows that the internal sensor electronic design (filters and detection stage) as well as the used data processing algorithm, limit its precision and accuracy by generating nonlinearities and biases. These issues avoid some applications like moving ones and imply that the algorithm used to process the sensor signals must be clearly presented in future articles.

scholarly journals Proteus II: Design and Evaluation of an Integrated Power-Efficient Underwater Sensor Node

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Wouter A. P. van Kleunen ◽  
Niels A. Moseley ◽  
Paul J. M. Havinga ◽  
Nirvana Meratnia
Keyword(s):  
Sensor Node ◽  
Low Cost ◽  
Environmental Parameters ◽  
Sensor Data ◽  
Modulation Scheme ◽  
Time Of Arrival ◽  
Analog To Digital ◽  
Power Efficient ◽  
Toa Estimation ◽  
And Performance

We describe the design and evaluation of an integrated low-cost underwater sensor node designed for reconfigurability, allowing continuous operation on a relatively small rechargeable battery for one month. The node uses a host CPU for the network protocols and processing sensor data and a separate CPU performs signal processing for the ultrasonic acoustic software-defined Modulator/Demodulator (MODEM). A Frequency Shift Keying- (FSK-) based modulation scheme with configurable symbol rates, Hamming error correction, and Time-of-Arrival (ToA) estimation for underwater positioning is implemented. The onboard sensors, an accelerometer and a temperature sensor, can be used to measure basic environmental parameters; additional internal and external sensors are supported through industry-standard interfaces (I2C, SPI, and RS232) and an Analog to Digital Converter (ADC) for analog peripherals. A 433 MHz radio can be used when the node is deployed at the surface. Tests were performed to validate the low-power operation. Moreover the acoustic communication range and performance and ToA capabilities were evaluated. Results show that the node achieves the one-month lifetime, is able to perform communication in highly reflective environments, and performs ToA estimation with an accuracy of about 1-2 meters.

scholarly journals Design of a Linear Voltage to Frequency Converter for Digital Audio Applications

2019 ◽  
Vol 9 (1) ◽  
pp. 4458-4464
Keyword(s):  
Low Cost ◽  
Frequency Converter ◽  
Digital Audio ◽  
Output Frequency ◽  
Digital Conversion ◽  
Analog To Digital ◽  
Frequency Converters ◽  
Analog To Digital Conversion ◽  
Frequency Counter ◽  
Audio Interfaces

Voltage to frequency converters are used in various types of analog to digital converters in suitable digital audio applications. One of the applications is the Audio Interface which has been considered. The Voltage to frequency converter (VFC) thus plays a major role in the analog to digital conversion. This paper proposes a low power VFC designed in 0.18 µm technology which in turn is used to design a low cost and a high-resolution analog to digital converter (ADC). The analog signal is given to the V-F converter and the VFC output is given to the frequency counter using a suitable link. This counter gives the digital output. The design is implemented in PSoC and the performance is analysed with the previous technologies. Parameters such as sensitivity, output frequency and power consumption are analysed. This V-F converter and ADC are used in the digital audio interface which is used for audio applications. With the proposed VFC and ADC, the interface produced a good SNR compared to the conventional audio interfaces.

Advanced Analog-to-Digital Conversion Using Voltage-to-Frequency Converters for Remote Sensors

2008 ◽  
Vol 381-382 ◽  
pp. 623-626 ◽  
Author(s):  
Sergey Y. Yurish
Keyword(s):  
High Performance ◽  
Frequency Conversion ◽  
Dynamic Range ◽  
Low Cost ◽  
Frequency Converter ◽  
Charge Balance ◽  
Digital Conversion ◽  
Analog To Digital ◽  
Remote Sensors ◽  
Analog To Digital Conversion

This paper presents an advanced analog-to-digital conversion technique based on a voltage-to-frequency-to-digital conversion that is suitable for remote sensors, telemetry applications and multichannel data acquisition systems. A voltage-to-frequency conversion part can be based, for example, on high performance, charge-balance voltage-to-frequency converter (VFC), where monostable is replaced by a bistable, driven by an external clock, or other existing high performance VFCs. The frequency-to-digital converter “bottleneck” problem in such promised ADC scheme was solved due to proposed advanced method of the dependent count for frequency-to-digital conversion. This ADC technique lets receive many advantages such as high accuracy, relatively low power consumption, low cost solution, wide dynamic range, great stability and faster conversion time in comparison with existing VFC-based techniques. The conversion rate (6.25 µs to 6.25 ms) in such ADC scheme is programmable, non-redundant, shorter than for pulse counting technique and comparable with successive-approximation and Σ- ADC.

Programmable Integrated Photonics

2020 ◽  
Author(s):  
José Capmany ◽  
Daniel Pérez
Keyword(s):  
Integrated Circuit ◽  
Performance Monitoring ◽  
Low Cost ◽  
Limiting Factors ◽  
External Control ◽  
Integrated Photonics ◽  
New Paradigm ◽  
Photonic Integrated Circuit ◽  
And Performance ◽  
Application Fields

Programmable Integrated Photonics (PIP) is a new paradigm that aims at designing common integrated optical hardware configurations, which by suitable programming can implement a variety of functionalities that, in turn, can be exploited as basic operations in many application fields. Programmability enables by means of external control signals both chip reconfiguration for multifunction operation as well as chip stabilization against non-ideal operation due to fluctuations in environmental conditions and fabrication errors. Programming also allows activating parts of the chip, which are not essential for the implementation of a given functionality but can be of help in reducing noise levels through the diversion of undesired reflections. After some years where the Application Specific Photonic Integrated Circuit (ASPIC) paradigm has completely dominated the field of integrated optics, there is an increasing interest in PIP justified by the surge of a number of emerging applications that are and will be calling for true flexibility, reconfigurability as well as low-cost, compact and low-power consuming devices. This book aims to provide a comprehensive introduction to this emergent field covering aspects that range from the basic aspects of technologies and building photonic component blocks to the design alternatives and principles of complex programmable photonics circuits, their limiting factors, techniques for characterization and performance monitoring/control and their salient applications both in the classical as well as in the quantum information fields. The book concentrates and focuses mainly on the distinctive features of programmable photonics as compared to more traditional ASPIC approaches.

The Use of Microcomputer Simulations in Undergraduate Neurophysiology Experiments

1987 ◽  
Vol 14 (3) ◽  
pp. 134-140 ◽  
Author(s):  
K.A. Clarke
Keyword(s):  
Low Cost ◽  
Animal Experiments ◽  
Theoretical Background ◽  
General Purpose ◽  
Microcomputer System ◽  
Laboratory Equipment ◽  
Teaching Objectives ◽  
Compound Action Potentials ◽  
Experimental Management ◽  
And Performance

Practical classes in neurophysiology reinforce and complement the theoretical background in a number of ways, including demonstration of concepts, practice in planning and performance of experiments, and the production and maintenance of viable neural preparations. The balance of teaching objectives will depend upon the particular group of students involved. A technique is described which allows the embedding of real compound action potentials from one of the most basic introductory neurophysiology experiments—frog sciatic nerve, into interactive programs for student use. These retain all the elements of the “real experiment” in terms of appearance, presentation, experimental management and measurement by the student. Laboratory reports by the students show that the experiments are carefully and enthusiastically performed and the material is well absorbed. Three groups of student derive most benefit from their use. First, students whose future careers will not involve animal experiments do not spend time developing dissecting skills they will not use, but more time fulfilling the other teaching objectives. Second, relatively inexperienced students, struggling to produce viable neural material and master complicated laboratory equipment, who are often left with little time or motivation to take accurate readings or ponder upon neurophysiological concepts. Third, students in institutions where neurophysiology is taught with difficulty because of the high cost of equipment and lack of specific expertise, may well have access to a low cost general purpose microcomputer system.

scholarly journals Experiments with Neural Networks in the Identification and Control of a Magnetic Levitation System Using a Low-Cost Platform

2021 ◽  
Vol 11 (6) ◽  
pp. 2535
Author(s):  
Bruno E. Silva ◽  
Ramiro S. Barbosa
Keyword(s):  
Neural Networks ◽  
Neural Control ◽  
Magnetic Levitation ◽  
Low Cost ◽  
Training Data ◽  
Neural Controllers ◽  
Levitation System ◽  
Internal Model Controller ◽  
Magnetic Levitation System ◽  
And Performance

In this article, we designed and implemented neural controllers to control a nonlinear and unstable magnetic levitation system composed of an electromagnet and a magnetic disk. The objective was to evaluate the implementation and performance of neural control algorithms in a low-cost hardware. In a first phase, we designed two classical controllers with the objective to provide the training data for the neural controllers. After, we identified several neural models of the levitation system using Nonlinear AutoRegressive eXogenous (NARX)-type neural networks that were used to emulate the forward dynamics of the system. Finally, we designed and implemented three neural control structures: the inverse controller, the internal model controller, and the model reference controller for the control of the levitation system. The neural controllers were tested on a low-cost Arduino control platform through MATLAB/Simulink. The experimental results proved the good performance of the neural controllers.

scholarly journals Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 785
Author(s):  
Chow Shing Shin ◽  
Yu Chia Chang
Keyword(s):  
High Resolution ◽  
Lattice Structure ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Dip Coating ◽  
Unit Cell ◽  
Digital Light Processing ◽  
Unit Cell Size ◽  
Wide Range ◽  
And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

Sign in / Sign up

Export Citation Format

Share Document